从 IONIC 3 中的资产文件夹下载 CSV 文件答案

【问题标题】：Download CSV file from assets folder in IONIC 3从 IONIC 3 中的资产文件夹下载 CSV 文件
【发布时间】：2019-02-24 08:24:27
【问题描述】：

我有一个demo-file.csv 文件，它在assets/csv 文件夹中，所以我如何从手机下载它，

这是我的 HTML 和组件代码。

HTML 代码

<button ion-button type="button" block (click)="downloadFile('assets/csv/demo-file.csv', 'demo-file.csv')">Download Demo File</button>

组件代码

 public downloadFile(link: any, fileName: any) {
      if (link) {
        let path = null;
        this.showWaitingLoading();
        if (this.platform.is('ios')) {
          path = this.file.documentsDirectory;
        } else {
          path = this.file.dataDirectory;
      }

      const transfer = this.transfer.create();

      transfer.download(link, path + fileName).then(entry => {
        this.dismissWaitingLoading();
        this.openFile(entry.toURL());
      }).catch(() => {
        this.dismissWaitingLoading();
        this.showToastMsg('error', "Something went wrong");
      });
     }
    }
/* ================= OPNE FILE FUNCTION ===========*/

public openFile(path: any) {
   this.fileOpener.open(path, 'application/*')
     .then(() => console.log('File is opened'))
     .catch((e: any) => console.log('Error openening file', e));
}

我无法下载文件，我的 PATH 中是否缺少任何东西？

【问题讨论】：

你不需要前导斜线吗？ /assets/csv/demo-file.csv?下载失败时会出现什么错误？
@David 我也尝试使用斜线，但没有成功。
那么你得到了什么错误？

标签： javascript angular ionic2 ionic3 file-transfer

【解决方案1】：

尝试使用Http get读取并写成Blob，示例代码如下，

export class csvPage {
  csvData: any[] = [];
  headerRow: any[] = [];

  constructor(public navCtrl: NavController, 
    public navParams: NavParams,
    private http: Http) {
      this.readCsvData();
  }

  private readCsvData() {
    this.http.get('assets/dummyData.csv')
      .subscribe(
      data => this.extractData(data),
      err => this.handleError(err)
      );
  }

  private extractData(res) {
    let csvData = res['_body'] || '';
    let parsedData = papa.parse(csvData).data;

    this.headerRow = parsedData[0];

    parsedData.splice(0, 1);
    this.csvData = parsedData;
  }

  downloadCSV() {
    let csv = papa.unparse({
      fields: this.headerRow,
      data: this.csvData
    });

    // Dummy implementation for Desktop download purpose
    var blob = new Blob([csv]);
    var a = window.document.createElement("a");
    a.href = window.URL.createObjectURL(blob);
    a.download = "newdata.csv";
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
  }

  private handleError(err) {
    console.log('something went wrong: ', err);
  }

}

【讨论】：

【解决方案2】：

您可以使用库...此外，HttpClient 可以为您读取数据为Blob。

npm i file-saver

// my.component.ts

import * as fileSaver from 'file-saver';

export class MyComponent {

  constructor(private http: HttpClient){}

  downloadFile(path: string) {
    this.startLoading();
    this.http.get(`${MY_APP_URL}/${path}`, { responseType: 'blob' })
      .pipe(tap(blob: Blob => fileSaver.saveAs(blob, 'your_csv_file_name.csv')))
      .subscribe(() => this.stopLoading(), err => this.handleErr(err));
  }
}

希望这会有所帮助:-)

【讨论】：

@Heerhaaw 我的文件位于 /src/assets/csv/demo-file.csv ，所以我可以在 ${MY_APP_URL}/${path} 中输入什么路径b>，那是我不知道
试试this.http.get('/assets/csv/demo-file.csv', ...)。

【解决方案3】：

HTML 代码

 <button ion-button type="button" block (click)="downloadFile('demo-file.csv')">Download Demo File</button>

组件代码

 declare var cordova: any; // declare Top Section of component
 public downloadFile(link: any) {
  if (link) {
    let path = null;
    this.showWaitingLoading();
    if (this.platform.is('ios')) {
    path = cordova.file.documentsDirectory;
  } else {
    path = cordova.file.dataDirectory;
  }

  const transfer = this.transfer.create();
  const imageLocation = `${cordova.file.applicationDirectory}www/assets/csv/${link}`;

  transfer.download(imageLocation, path + link).then(entry => {
    this.dismissWaitingLoading();
    this.openFile(entry.toURL());
  }).catch(() => {
    this.dismissWaitingLoading();
    this.showToastMsg('error', "Something went wrong");
  })
 }

 /* ================= OPNE FILE FUNCTION ===========*/
 public openFile(path: any) {
  this.fileOpener.open(path, 'application/*')
   .then(() => console.log('File is opened'))
   .catch((e: any) => console.log('Error openening file', e));
 }

请试试这个

【讨论】：